Phase-Noise Reduction in a CMOS-MEMS Oscillator Under Nonlinear MEMS Operation

In this paper, we will present an all-CMOS oscillator based on monolithically integrated MEMS resonators fabricated from the VIA layer (tungsten) of a 0.35 μm CMOS technology process. With this CMOS MEMS closed-loop system, the nonlinear MEMS frequency response due to the electrostatic actuation has been reconstructed. Using a phase-controlled closed-loop the frequency stability of the self-sustained oscillator at different nonlinear operation points has been analyzed, showing an optimal point belonging to the unstable region of the MEMS resonator.

I. Introduction

MEMS based oscillators are being considered a clear alternative to replace the off chip quartz crystals resonators in applications such as mobile devices, wearables, and the Internet of Things (IoT), where power consumption, miniaturization, production cost and large scale integration are being demanded [1]–[3].